Chemical patterning of graphene is relevant in several different domains of science and technology with exciting possibilities in electronics, catalysis, sensing, and photonics. Despite intense efforts, spatially controlled, (multifunctional) covalent chemical patterning of graphene is not straightforward to achieve. The lack of control primarily originates from the inherently poor reactivity of the basal plane of graphene which necessitates the use of harsh chemistries. In my talk, I will present two examples of covalent chemical patterning of graphene and graphite using diazonium chemistry. In the first case, spatially resolved multicomponent covalent chemical patterning of single layer graphene was achieved using a facile and efficient method. Three different functional groups could be covalently attached to the basal plane in dense, well-defined micrometer wide patterns using a combination of lithography and a self-limiting variant of diazonium chemistry requiring no need for graphene activation. The layer thickness of the covalent films could be controlled down to 1 nm. In the second case, i will present sub-10 nm chemical patterning of graphite achieved using the electrochemical diazonium chemistry.  Here, an elegant combination of covalent and non-covalent chemistry was used to achieve 5-6 nm wide linear chemical patterns with excellent pattern transfer fidelity. Throughout the discussion, i will highlight the critical role of scanning probe microscopy, namely STM, AFM and AFM-IR in providing critical spatial and spatiochemical information at the nanometer scale where conventional analytical techniques fail to provide accurate information.